Fixed the hotseat placement in RTL mode

Updated logic that computest the hotseat shift.

Fixes: 372014534
Flag: com.android.wm.shell.enable_bubble_bar
Test: Manual. Put device into 3 buttons navigation mode, force RTL.
Hotseat is placed next to the navigation buttons bar.

Change-Id: Ie7b6be11a093ffa4006182bdc0b73018ba799246